From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-0.8 required=3.0 tests=DKIM_SIGNED,DKIM_VALID, DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SPF_HELO_NONE, SPF_PASS autolearn=no autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id A8B10C2BA83 for ; Fri, 14 Feb 2020 18:15:55 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 784F22168B for ; Fri, 14 Feb 2020 18:15:55 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=zx2c4.com header.i=@zx2c4.com header.b="la2J5lSw" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S2404602AbgBNSPu (ORCPT ); Fri, 14 Feb 2020 13:15:50 -0500 Received: from frisell.zx2c4.com ([192.95.5.64]:51751 "EHLO frisell.zx2c4.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726191AbgBNSPl (ORCPT ); Fri, 14 Feb 2020 13:15:41 -0500 Received: by frisell.zx2c4.com (ZX2C4 Mail Server) with ESMTP id 7beb9041 for ; Fri, 14 Feb 2020 18:13:32 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha1; c=relaxed; d=zx2c4.com; h=mime-version :references:in-reply-to:from:date:message-id:subject:to:cc :content-type; s=mail; bh=2xKsb8PS9uL3oIiu01Li12DoOZc=; b=la2J5l SwYdd00SWy5obl8QUBM4K1JcE9s386M3GU8J9S2FWlrLfwecxy1NEtZcrPVS5bvb 8kWMISwz3uFsS+nBQGLKlWJZkonuG+9mevdMFlrMSJz8US0olzZHFpmdJ1shgScz UVRL/qRJYSwEuVP7jyNqAinfStNSkzrkwao+gAQmyS+tEWkXhnC/QFrso3WV+f82 C+uA+qJWiMTfLmOwEjnQ1oCOsy8lfTT3L5/Ff0hCtBPbZIBGYJFpczuYvQldAoA2 hD2ozme0YvhubFyFiuqM3qe0qV6Py7rqaGoIBCsltAOfiU88xcQ+D9Zj70M3m928 do9eB417h8a2ESMg== Received: by frisell.zx2c4.com (ZX2C4 Mail Server) with ESMTPSA id 4e2d3708 (TLSv1.2:ECDHE-RSA-AES256-GCM-SHA384:256:NO) for ; Fri, 14 Feb 2020 18:13:31 +0000 (UTC) Received: by mail-oi1-f180.google.com with SMTP id a142so10263401oii.7 for ; Fri, 14 Feb 2020 10:15:39 -0800 (PST) X-Gm-Message-State: APjAAAWqN/3tDviktX+OQXr7TVRSr5qPVakAmcqAAqSI8pCgS3vOYjCI Ymfa4LLCaGKxUhsf7b87QoVfpgWjteYAaOTZA3M= X-Google-Smtp-Source: APXvYqzc7PUt4DGPZX8iSs1laIe7+c6yOsAgWMfdVO4uVY7HTKHpRn8i58W1frmncIKZN4k8hGzzqNZOCowZp0/GpfM= X-Received: by 2002:a05:6808:a8a:: with SMTP id q10mr2687179oij.66.1581704138212; Fri, 14 Feb 2020 10:15:38 -0800 (PST) MIME-Version: 1.0 References: <20200214173407.52521-1-Jason@zx2c4.com> <20200214173407.52521-4-Jason@zx2c4.com> <135ffa7a-f06a-80e3-4412-17457b202c77@gmail.com> In-Reply-To: <135ffa7a-f06a-80e3-4412-17457b202c77@gmail.com> From: "Jason A. Donenfeld" Date: Fri, 14 Feb 2020 19:15:26 +0100 X-Gmail-Original-Message-ID: Message-ID: Subject: Re: [PATCH v2 net 3/3] wireguard: send: account for mtu=0 devices To: Eric Dumazet Cc: David Miller , Netdev , Eric Dumazet Content-Type: text/plain; charset="UTF-8" Sender: netdev-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: netdev@vger.kernel.org On Fri, Feb 14, 2020 at 6:56 PM Eric Dumazet wrote: > Oh dear, can you describe what do you expect of a wireguard device with mtu == 0 or mtu == 1 > > Why simply not allowing silly configurations, instead of convoluted tests in fast path ? > > We are speaking of tunnels adding quite a lot of headers, so we better not try to make them > work on networks with tiny mtu. Just say no to syzbot. The idea was that wireguard might still be useful for the persistent keepalive stuff. This branch becomes very cold very fast, so I don't think it makes a difference performance wise, but if you feel strongly about it, I can get rid of it and set a non-zero min_mtu that's the smallest thing wireguard's xmit semantics will accept. It sounds like you'd prefer that?